<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        @media (width:375px) {
            html{
                /* 屏幕大小分为十等分 */
             font-size: 37.5px;
            }
        }
        @media (width:414px) {
            html{
             font-size: 41.4px;
            }
        }
        .box{
         width: 2rem;
         height: 2rem;
         background-color: brown;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>